The 3rd Generation Mobile Telecommunications standards (3G) for providing wireless mobile voice and data communications is being slowly replaced by its successor 4th Generation Mobile Telecommunications (4G). Mobile carriers have begun to upgrade their 3G networks to provide 4G coverage, but the transition to 4G coverage will not occur overnight. Instead, mobile carriers have been upgrading portions of their networks to provide 4G service while the rest of the networks still operate using the 3G standards. As a result, subscribers may encounter parts of the network that provide 3G services while other portions of the network provide for 4G services. Furthermore, a subscriber who has established a 3G voice and/or data connection with the network may move from an area of the network where 3G services are provided to an area where 4G services are provided. Alternatively, a subscriber who has established a 4G voice and/or data connection with the network may move from an area of the network where 4G services are provided to an area where only 3G services are provided. The network and/or the subscriber's user device needs to be able recognize that this situation is about to occur and be able to complete a seamless vertical handoff from a first base station to a second base station.
Current methods for identifying whether 4G connectivity is available are based on an unconditional scanning algorithm that continuously searches for the 4G network with back off when there is no 4G detected. This method is generally not efficient since the scanning consumes additional power. Continuous scanning can seriously degrade battery life of a mobile device. Furthermore, the back off algorithm can cause the mobile device to not detect a 4G network in a mobile situation where the user moves the device from an area that has no 4G coverage into an area that has 4G coverage. As a result, the device can enter into an area where 4G coverage is available, but the device does not detect the 4G coverage and initiate a handoff.